1. Field of the Invention
The present invention relates to an ultrasonic adhering method of adhering a sheeted resin material by heating and fusing by means of ultrasonic oscillation. It also relates to an apparatus thereof.
2. Description of the Related Art
An adhering apparatus by means of ultrasonic oscillation that has been known hitherto comprises an ultrasonic oscillator for generating ultrasonic vibration, and an ultrasonic oscillation horn provided in the ultrasonic oscillator. It serves to heat and fuse an object by pressing the ultrasonic oscillation horn to a material to be adhered to each other and oscillating it.
A control method in this ultrasonic adhesion includes a method of detecting the horn temperature and controlling amplitude of ultrasonic oscillation of the horn. In this control method, for example, as disclosed in Japanese Patent Publication No. 2-35661 or Japanese Patent Laid-open Publication No. 63-315223, the temperature is detected as reference temperature by a temperature sensing element such as thermistor mounted to a holding member or a receptacle, and the amplitude of ultrasonic oscillation is made to be increased when the temperature is lower than the reference temperature, or decreased when higher.
Further, as disclosed in Japanese Patent Laid-open Publication No. 62-140823 or Japanese Patent Laid-open Publication No. 5-299480, there has been also proposed a control means for detecting temperature of an ultrasonic horn having a heating device such as heater, and controlling the heating device so as to keep the horn at a constant temperature.
In the aforementioned prior art of controlling the amplitude of ultrasonic oscillation, when the amplitude is made to increase in ultrasonic adhesion, local failure may occur in the adhesion material such as a sheeted resin material. This is because sudden energy addition occurs due to increase of amplitude of the ultrasonic oscillation. In the case of a thin-sheeted material, it is likely to be broken locally in its pressed area. Still worse, the condition of inducing local failure is not constant, so that it was difficult to control the limit of energy accurately so as not to induce local failure.
Furthermore, the method of keeping the ultrasonic horn at a constant temperature is applicable in the case of fusing at a relatively high temperature such as welding of metal. In the case of adhesion of resin or the like, on the other hand, the fusion temperature is relatively low, and a heater or any other heating means cannot be provided. To the contrary, since the temperature of the ultrasonic horn rises due to continuous use of ultrasonic adhesion, it is required to suppress the temperature rise. To suppress this temperature rise, however, it is not sufficiently efficient to cool it by air blow, but when a cooling device is installed, the equipment increases and the production cost would rise. In particular, in the ultrasonic adhesion of sheeted resin materials, when the temperature becomes too high, the materials become brittle. Thus, temperature control of the horn has been a serious problem.
The invention is made in the light of the aforementioned problems of the prior art, and it is hence an object thereof to provide an ultrasonic adhering method and apparatus capable of performing appropriate adhesion in a simple construction, regardless of external environments.
In order to achieve the foregoing object, according to the present invention, there is provided an ultrasonic adhering method for bringing a horn of an ultrasonic oscillator to contact with a sheeted resin material while the sheeted resin material is overlaid on an object to be adhered and oscillating the horn ultrasonically, being characterized in that temperature of the horn is sensed, and the oscillation time in a state of the horn being in contact with the sheeted resin material is set to be in a negative correlation with respect to the temperature of the horn, and the sheeted resin material is fused to the object. The temperature of the horn is sensed immediately before the sheeted resin material is made to adhere by the horn.
The object to be adhered may be fastener tapes having coupling elements of a slide fastener, and the sheeted resin material is reinforcing materials such as reinforcing tapes to be fused to portions of the tapes, i.e. at ends of the fastener tapes, where a bottom stop is to be mounted.
Furthermore, according to the present invention, there is provided an ultrasonic adhering apparatus including an ultrasonic oscillator for generating ultrasonic vibration, a horn provided in this ultrasonic oscillator for oscillating ultrasonically, a temperature sensor for sensing the temperature of the horn, and a controlling unit for detecting the temperature of the horn, and controlling oscillation time of the ultrasonic oscillator in a state of the horn being contact with a sheeted resin material in such a manner that the oscillation time has a negative correlation with respect to the temperature of the horn. The temperature sensor is of non-contact type, which senses the temperature of the horn near the object to be fused.